An ES cell is called an embryonic stem cell, and was found from a mouse embryo in 1981 and from a human embryo in 1998. Research for constructing tissues or organs using the ES cell as a cell having the ability to change into a variety of kinds of cells other than cells constituting placenta (which is called as “pluripotency”) has mainly been conducted. However, since the ES cell utilizes a fertilized egg which becomes a life when it grows smoothly, it has a major ethical problem. As another major problem, there is a problem of rejection. Even if differentiated cells or organs which were produced based on the ES cell are transplanted into a patient, there is a possibility that the immune system recognizes them as a nonself and attacks them.
In order to solve these problems of the ES cell, a group of Shinya Yamanaka Professor of Kyoto University developed a cell having the ability to change into a variety of kinds of cells from a skin cell which does not usually differentiate into a cell having other function, and named it as an iPS cells. It was shown that, when four factors called Yamanaka factors (Oct3/4, Sox2, Klf4, c-Myc) are introduced into a mouse or human skin cell using a retrovirus vector, initialization of the cell occurs, and a cell having pluripotency like the ES cell can be made [Non-Patent Document 1, and Non-Patent Document 2]. Since the cell used at this time is derived from a somatic cell such as a differentiated skin of a patient itself, when a cell differentiated from the iPS cells is transplanted into a patient, the immune system recognizes the organ as a self, and does not reject transplantation. By the finding of the iPS cells, two problems of “life ethics” and “rejection reaction” harbored by the ES cell have been cleared, however, the technique for standardizing the iPS cells is on the way of development and could not have completely overcome a problem of cancerization of a cell.
A process for producing a reprogrammed embryonic stem cell (ES)-like cell using a bacterium, Mycobacterium leprae or a component thereof has been proposed in Patent Document 1. Patent Document 1 describes a process for producing a reprogrammed ES-like cell by contacting and infecting an adult differentiated cell with a bacterium, Mycobacterium leprae itself, and a cell produced by this method, and describes that the bacterium which was contacted and infected exists in the produced ES-like cell. However, a bacterium, Mycobacterium leprae is a causation bacterium for leprosy Bacillus, and there is concern for safety in application to regenerative medicine.
Further, the present inventors have reported a process for producing a pluripotent cell from a somatic cell, by infecting the somatic cell with Lactobacillus or Bacillus natto which is a bacterium having the fermenting ability (Patent Document 2, Non-Patent Document 3). Still further, the present inventors have filed a patent application directed to a process for producing a pluripotent cell from a somatic cell, by using a crude extraction component from Lactobacillus, as PCT/JP2014/056948 (International Publication WO 2014/167943).